1. Field of the Invention
The invention relates to an elliptical machine, more particularly to an elliptical machine that permits twisting movements of an upper body of a user.
2. Description of the Related Art
As shown in FIG. 1, a conventional elliptical machine 1 includes a machine body 11, a transmission unit 12, a handle unit 13, and a pedal unit 14.
The machine body 11 includes a support base 111, and an upright structure 112 extending upwardly from the support base 111. The transmission unit 12 is mounted rotatably to the support base 111, and is rotatable about a reference axis 15. The transmission unit 12 is disposed on a virtual vertical plane 16, which is perpendicular to the reference axis 15.
The handle unit 13 includes a rotary shaft 131 mounted rotatably on the upright structure 112, and left and right handles 133, 134 disposed on two opposite ends of the rotary shaft 131. The rotary shaft 131 has a rotation axis 135 that is parallel to the reference axis 15.
The pedal unit 14 includes a left pedal rod 141 and a right pedal rod 142. Each of the left and right pedal rods 141, 142 is pivoted to a respective one of the left and right handles 133, 134 at one end, and is pivoted to the transmission unit 12 at the other end. The left and right pedal rods 141, 142 are respectively disposed on two opposite sides of the virtual vertical plane 16. Foot plates 1411, 1421 of the left and right pedal rods 141, 142 respectively move along vertical elliptical paths that extend in planes parallel to the virtual vertical plane 16.
The left and right pedal rods 141, 142 of the conventional elliptical machine 1 can allow a user's feet to move along the vertical elliptical paths so as to achieve the effects of exercise. However, since the rotation axis 135 of the rotary shaft 131 is parallel to the reference axis 15, and since the handle unit 13, the pedal unit 14, and the transmission unit 12 are pivoted to each other using simple pivot connections, the left and right pedal rods 141, 142 merely swing back and forth along the vertical elliptical paths. Consequently, the amount of exercise the user obtains from using the conventional elliptical machine 1 is limited. That is, only a small number of the muscles on the upper and lower legs are exercised, and only a minimal exertion is required by the user in exercising these muscles